A conventional variable gear ratio steering (VGRS) apparatus varies steered angle of steered wheels (vehicle wheels) of a vehicle relative to steering angle of a steering wheel. The VGRS apparatus (for example, refer to patent documents 1 to 4) conventionally has a lock mechanism for fixing a steering ratio. The lock mechanism includes a lock pin and a latch member for latching the lock pin.    (Patent document 1) JP 2001-287660A    (Patent document 2) JP 2004-058743A    (Patent document 3) JP 2004-114857A    (Patent document 4) JP 2005-350036A
However, according to the patent documents 1 to 4, the lock mechanism for fixing the steering ratio is provided separately from a gear mechanism, which varies the steering ratio. The apparatus therefore necessarily becomes large in overall size.